What does dative + быть mean?

Question

Can you explain the phrase below, why is the dative used, what is the meaning, what is the grammatical principle at play here?

Ну где ему быть...

For clarification the next line is:

...вон, в котельной

Answer 1

Something like this happens at transformation into brief impersonal form:

Где он может быть → Где ему можно быть → Где ему быть

So you might think of 'dativeness' here literally as of something given to him, with 'given' omitted:

Ну где ему (дано, положено, возможно, суждено) быть? (Там он и находится - сам подумай.)

Well, where is he supposed to be? You could guess where he is.

Answer 2

"Ну где ему быть..." = "Ну где он может быть..." При чем и одно, и другое предложение может быть как вопросительным, так и повествовательным.

Сама фраза звучит достаточно обыденно, ну а как так получается, что мы употребляем дательный падеж таким специфическим образом - так сразу и не ответишь ;-) Скорее всего, это остатки от старой языковой конструкции "дательный самостоятельный" (dativus absolutus). Например, "Идущу же ему въспять, размыслив рече дружине своей..." ("Повесть временных лет") (As he was going back, having thought, he said to his men...)

Answer 3

The dative case (по-русски дательный падеж, от слова дать, давать) is a grammatical case generally used to indicate the noun to which something is given, i.e. to addressee, destination.

One of the scheme is Noun + to + Noun:

  a gift to one's friend 
     подарок другу

or, addressee/destination expressed by lexical meaning

    we have got to like it
   это должно нам нравиться
               \
                \__ Dative
 

One might rewrite the sentence

        Ему быть.

       Где ему быть.
    Где оно ему быть.
    Где это ему быть.
  Где это оно ему быть.

The meaning here is practically the same, but the full sentences with a subject abbreviated to subjectless
Где ему быть.
See also my answer for subjectless sentences.

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You cannot think about the whole sentence as Where can it/she/he be? or Where is //he? because its short form. Actually, it has two meanings:

a) где ему быть               -- unsure, where is //he; in some place.
                                 You have supposed the scene to be there, where is //he.


б) где ему быть (кем-то, чем-то, каким-то)   -- to be someone,  to come from,  
          └───────────────┬───────────────┘     be a match (for), to think they are like.
                      = стать
                        несов.: становиться

Answer 4

That's not a very widely used construction, and I can think of only one more or less proper use of it.

It is generally used as an answer to a question, like:

-А он в тюрьме? (Is he in jail?)

-Ну где ему быть...

It means something like "where else?". It's kinda "yes", plus you stress the obviousness of that, like in: "Of course he is! Where else is he supposed to be?"

The same way you can put it with other verbs, like "работать"(work), "жить"(live) etc.

Not sure about grammar of dative case here. To me it's just a common expression, sometimes they are not entirely grammatically accurate.

EDIT1: You've appended your phrase. Yeah, pretty much, it sounds like an answer: "Where else? He's there, in the boiler-house.". And yes, this particular expression is constructed as где + subject in dative + infinitive. You can put a pronoun, a name, a noun etc. there.

Answer 5

Based on the by Highstaker's example:

Ну где ему быть?

Can be expanded to:

Ну где ему ещё быть, как не в тюрьме?

Which is equal in meaning to this, with more common grammar.

Ну где ещё он может быть, как не в тюрьме?

With all non-verbal implications this means:

Since he went to prison, there's no chance for him to be anywhere else. Where else could he be? And I'm disappointed by him being in prison and/or by yourself asking that question.

The form dative + verb means that the subject is obliged, predicted, destined or doomed to the verb-described action. E. g.:

Чему быть - того не миновать.

This proverb means What should happen, cannot be avoided. It expresses accepting or giving up to destiny, be it good or bad.

One more example, from the song "Двери Тамерлана" by "Мельница", a folk-rock band, telling about a woman's destiny:

А мне вышивать
Оливковый лён,
Слезами ронять
Монистовый звон.

Answer 6

Ну[,] где ему быть is a kinda rhetorical question introducing the answer вон, в котельной.
The first comma, if present, detaches the initial Ну up to the level of a separate clause — very similar to the English Well,... Without that comma Ну is a particle with the meaning of ‘Hmm’ or just an extra place to bear an emotional charge of the clause.
Possible translations:
  W[ell, w]here can he be?
  Where can he be anyway?

Now the main part of your question: a construction ‘dative + infinitive’.
It can be a part of a larger pattern ‘dative + infinitive + modal adverbial’ which is probably more 'parsable' for a learner:
Мне(2) нужно(1) позвонить(3). (dat. mod.-adv. inf.)
It is necessary(1) for me(2) to make a phone call(3). ('parsing' in English)
  I need to make a phone call. (a translation)

In certain cases a modal adverb(ial) can be implied making the above parsing possible:
Мне работать?! >> Мне [надо] работать?!
[Is it needful for] me to work?! (a 'parsing')
 Am I to work?! or Need I work?! (You’re crazy supposing that! Don’t even try…) — a translation.

And here’s the general and simple way to retell that construction in English, I believe:

ru: dative + infinitive
en: Subject + ‘be’ conjugational form + ‘to’ + infinitive
гдеемубыть? :: whereishetobe?

But the scheme above is just a clue to grasp that pattern. The modalities can differ: of a Russian phrase and of its English 'analogue' deduced through that scheme.
If there is just ‘dative + infinitive’ in the clause, without a modal adverbial expressing the modality explicitly, the general impact on the meaning of a clause seems to be the following: it makes a message extra-personal, as if actions (denoted by inf.) do not depend on actors (denoted by dat.) and are determined by something else. In case of non-interrogative clauses it can be formulated as the modality of a destined fact (action).

examples
Саду цвесть — The garden to blow
Чему быть, того не миновать. — What is to be can’t be escaped.
Четвёртому Риму не бывать! — (I spell) The Forth Rome not to come into being! or The Forth Rome shall not come into being!
Кому идти за пивом? — Who is/will be 'the chosen' to go to buy some beer?
Зачем ему приходить сюда? — Why is he to come here? What’s the need of/for his coming here?
Откуда мне знать? — How do I know? Who/What could make me informed? — Obviously none!

BTW
было makes all in the past tense:
Мне(2) нужнобыло(1) позвонить(3).
Itwasnecessary(1) for me(2) to make a phone call(3). ('parsing' in English)
 I had to make a phone call. (a translation)

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I suspect the construction could be theorized as some non-indicative mood. But I answered without knowing the (historical/theoretical) backgrounds for ‘dative+infinitive’ in Russian — I’m sure that background is interesting and helpful, should someone provide it…
see also (in Ruusian)